Method of eliminating fading



Patented Mar. 15, 1932 UNITED STATES PATENT OFFICE JULIUS WEIN'BERGER, OF NEW YORK, N. Y., ASSIGNOR TO RADIO GORPORATION OF AMERICA, A CORPORATION OF DELAWARE METHOD OF ELIMINA'IIN'G FADING No Drawing.

This invention relates to the art of radio telegraph signalling and deals more specifically with a method for eliminating fading in short Wave radio telegraph signal transmission.

In accordance with a specific embodiment of this invention the short wave radio frequency carrier wave is modulated by means of a plurality of audio frequencies generated by several separate oscillators. The "arious modulator frequencies difier from each other by 1,000 cycles per second. For example, the short wave carrier may be modulated by means of an audio frequency wave composed of 1,000, 2,000, 3,000, 4,000, or 5,000 cycles,

or even higher frequencies as required in order to accomplish the result. It follows from this, that the wave form which modulates the carrier frequencies is a 1,000 cycle tone, carrying strong higher harmonics.

In the operation of the transmission system in accordance with the present invention it will be seen that when the carrier wave is transmitted together with a number of side bands, the adjacent waves differ from each other by 1,000 cycles. At the receiving end ordinary detection is used, Without heterodyning. Now, if the carrier and all of the side bands get through during the transmission of a signal, a shrill 1,000 cycle tone will be heard. If only two adjacent side bands get through, a 1,000 cycle tone will also still be heard. There are, therefore, numerous possibilities, by the combination of the carrier with one or more side bands, or by combinations among the side bands themselves, of obtaining a 1,000 cycle tone at the receiving station; even if a number of component radio frequencies originally transmitted dropped out momentarily, due to fading between the transmitter and receiver. It therefore follows, that at the receiver the tone will fluctuate in quality and intensity, but the signal will not be destroyed due to fading.

The specific apparatus used as the oscillation generators, etc., as well as the modulation and the receiving means used in connection with the present invention may be of any of the well known types now available.

Application filed September 15, 1927. Serial No. 219,569.

JULIUS WEINBERGER. 

